Material handling systems have been commonly employed for receiving a continuous flow of materials of various types, sizes, and consistencies and for performing various processing techniques upon these materials as they are transported from one station to another. For example, municipal waste handling systems are adapted to receive a continuously flowing supply of commingled waste materials, transport the materials to a device such as a shredder where the materials are reduced to a maximum preselected size, and then transport the shredded materials to a collection area for storage or subsequent processing such as classification, incineration, or the like.
It is well known that municipal waste, for example, contains a wide variety of miscellaneous components such as garbage, paper, aluminum and tin cans, plastic items, textiles, and large steel and iron items such as castings, for example. It is necessary that large items be considerably reduced in size where the commingled materials are to be further processed, such as where subsequent classification is to be performed. For such size reduction it is required that the received commingled materials be moved through a suitable shredder which employs a system of knives, hammers, or grinding elements to reduce the overall size of the materials to a selected maximum, such as twelve inches, one inch, or other selected dimension.
Shredders of conventional construction, however, as a result of such heavy duty use are often subject to unexpected or relatively sudden discontinuance of operation or breakdown such as might be caused, for example, by jamming or clogging, or by damage to the size-reducing knife or hammer elements, or for other reasons. In such cases it has been necessary to shut down the operation of the entire system or of a substantial portion thereof, while the damage to the shredder is being repaired or while any other reason for the breakdown is being rectified. Obviously, such shutting down of a system of this character is highly undesirable for many reasons. For example, a system of this type is designed to process a selected relatively large number of tons of material during each hour of operation. Shutting down is consequently expensive in not only loss of processed materials value, but also in undesired reduction in operating manpower.